import 'package:collection/collection.dart';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../data/bible.dart';
import '../models/tracker.dart';
import '../services/last_location.dart';
import '../services/tracker_service.dart';
import '../widgets/theme.dart';
import '../widgets/tracker_tile.dart';
import 'book_screen.dart';
import 'create_tracker_screen.dart';
import 'tracker_screen.dart';

class HomeScreen extends ConsumerStatefulWidget {
  const HomeScreen({super.key});

  @override
  ConsumerState<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends ConsumerState<HomeScreen> {
  bool _restoreAttempted = false;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => _maybeRestore());
  }

  void _maybeRestore() {
    if (_restoreAttempted || !mounted) return;
    _restoreAttempted = true;

    final LastLocation? pending = ref.read(pendingRestoreProvider);
    if (pending == null) return;
    final List<Tracker> trackers = ref.read(trackerServiceProvider);
    final Tracker? tracker = trackers.firstWhereOrNull(
      (Tracker t) => t.id == pending.trackerId,
    );
    if (tracker == null) return;

    final NavigatorState navigator = Navigator.of(context);
    navigator.push<void>(
      MaterialPageRoute<void>(
        settings: RouteSettings(name: '/tracker/${tracker.id}'),
        builder: (_) => TrackerScreen(trackerId: tracker.id),
      ),
    );
    final int? bookIndex = pending.bookIndex;
    if (bookIndex != null && bookIndex >= 0 && bookIndex < Bible.books.length) {
      navigator.push<void>(
        MaterialPageRoute<void>(
          settings: RouteSettings(
            name: '/tracker/${tracker.id}/book/$bookIndex',
          ),
          builder: (_) =>
              BookScreen(trackerId: tracker.id, bookIndex: bookIndex),
        ),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    final List<Tracker> trackers = ref.watch(trackerServiceProvider);
    return Scaffold(
      appBar: AppBar(title: const Text('My Bible Tracker')),
      body: trackers.isEmpty
          ? const _EmptyState()
          : ListView.separated(
              padding: const EdgeInsets.all(AppTokens.spaceL),
              itemCount: trackers.length,
              separatorBuilder: (_, _) =>
                  const SizedBox(height: AppTokens.spaceM),
              itemBuilder: (BuildContext context, int index) {
                final Tracker tracker = trackers[index];
                return TrackerTile(
                  tracker: tracker,
                  onTap: () => Navigator.of(context).push<void>(
                    MaterialPageRoute<void>(
                      settings: RouteSettings(name: '/tracker/${tracker.id}'),
                      builder: (_) => TrackerScreen(trackerId: tracker.id),
                    ),
                  ),
                  onLongPress: () => _showTrackerMenu(context, ref, tracker),
                );
              },
            ),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: () => Navigator.of(context).push<void>(
          MaterialPageRoute<void>(builder: (_) => const CreateTrackerScreen()),
        ),
        icon: const Icon(Icons.add),
        label: const Text('New Tracker'),
      ),
    );
  }

  Future<void> _showTrackerMenu(
    BuildContext context,
    WidgetRef ref,
    Tracker tracker,
  ) async {
    final _TrackerMenuAction? action =
        await showModalBottomSheet<_TrackerMenuAction>(
          context: context,
          showDragHandle: true,
          builder: (BuildContext context) {
            return SafeArea(
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: <Widget>[
                  ListTile(
                    leading: const Icon(Icons.edit_outlined),
                    title: const Text('Rename / recolor'),
                    onTap: () =>
                        Navigator.of(context).pop(_TrackerMenuAction.edit),
                  ),
                  ListTile(
                    leading: const Icon(Icons.refresh),
                    title: const Text('Reset progress'),
                    onTap: () =>
                        Navigator.of(context).pop(_TrackerMenuAction.reset),
                  ),
                  ListTile(
                    leading: const Icon(Icons.delete_outline),
                    iconColor: Theme.of(context).colorScheme.error,
                    textColor: Theme.of(context).colorScheme.error,
                    title: const Text('Delete'),
                    onTap: () =>
                        Navigator.of(context).pop(_TrackerMenuAction.delete),
                  ),
                  const SizedBox(height: AppTokens.spaceS),
                ],
              ),
            );
          },
        );
    if (action == null || !context.mounted) return;
    switch (action) {
      case _TrackerMenuAction.edit:
        await Navigator.of(context).push<void>(
          MaterialPageRoute<void>(
            builder: (_) => CreateTrackerScreen(existing: tracker),
          ),
        );
      case _TrackerMenuAction.reset:
        await _confirmAndRun(
          context,
          title: 'Reset progress?',
          message:
              'All checked chapters for "${tracker.name}" will be cleared.',
          destructive: true,
          run: () =>
              ref.read(trackerServiceProvider.notifier).reset(tracker.id),
        );
      case _TrackerMenuAction.delete:
        await _confirmAndRun(
          context,
          title: 'Delete tracker?',
          message: '"${tracker.name}" will be removed permanently.',
          destructive: true,
          run: () =>
              ref.read(trackerServiceProvider.notifier).delete(tracker.id),
        );
    }
  }

  Future<void> _confirmAndRun(
    BuildContext context, {
    required String title,
    required String message,
    required bool destructive,
    required Future<void> Function() run,
  }) async {
    final bool? confirmed = await showDialog<bool>(
      context: context,
      builder: (BuildContext context) => AlertDialog(
        title: Text(title),
        content: Text(message),
        actions: <Widget>[
          TextButton(
            onPressed: () => Navigator.of(context).pop(false),
            child: const Text('Cancel'),
          ),
          FilledButton(
            style: destructive
                ? FilledButton.styleFrom(
                    backgroundColor: Theme.of(context).colorScheme.error,
                  )
                : null,
            onPressed: () => Navigator.of(context).pop(true),
            child: const Text('Confirm'),
          ),
        ],
      ),
    );
    if (confirmed ?? false) {
      await run();
    }
  }
}

enum _TrackerMenuAction { edit, reset, delete }

class _EmptyState extends StatelessWidget {
  const _EmptyState();

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(AppTokens.spaceXXL),
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: <Widget>[
            Icon(
              Icons.menu_book_outlined,
              size: 72,
              color: Theme.of(context).colorScheme.primary,
            ),
            const SizedBox(height: AppTokens.spaceL),
            Text(
              'Start your first tracker',
              style: Theme.of(context).textTheme.titleLarge,
              textAlign: TextAlign.center,
            ),
            const SizedBox(height: AppTokens.spaceS),
            Text(
              'Create a tracker to mark the chapters you have read. '
              'Read at your own pace — there are no deadlines.',
              textAlign: TextAlign.center,
              style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                color: Theme.of(context).colorScheme.onSurfaceVariant,
              ),
            ),
          ],
        ),
      ),
    );
  }
}